Nd isotopic evidence for the position of southernmost Indian terranes within East Gondwana

Brandon, A. D.; Meen, James K.

doi:10.1016/0301-9268(94)00047-u

Cited by 56 publications

(29 citation statements)

References 36 publications

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“…Zircon ages from rocks of igneous and sedimentary derivation in the KKB range from 0.5 to 2.4 Ga, whereas metamorphic ages are around 500-550 Ma Santosh et al 1992Santosh et al , 2003Santosh et al , 2005aBartlett et al 1995;Braun et al 1998;Braun and Bröcker 2004;Collins and Santosh 2004). Nd model ages suggest that granulite proltoliths were generated between 2.2 and 1.2 Ga (Brandon and Meen 1995;Harris et al 1994;Bartlett et al 1995), which is consistent with zircon ages reported by Santosh et al (2003). It is interesting to note that cores of some zircon grains as old as 3.07 and 3.70 Ga have been recorded by Santosh et al (2003) from the metasedimentary Khondalite Group rocks.…”

Section: Geologysupporting

confidence: 73%

High radiogenic heat production in the Kerala Khondalite Block, Southern Granulite Province, India

Ray

Roy

Srinivasan

2007

Int J Earth Sci (Geol Rundsch)

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In situ radioelemental (K, U and Th) analysis and heat production estimates have been made at 59 sites in the Kerala Khondalite Block (KKB) of the Southern Granulite Province (SGP) of India. Together with the in situ analyses on granulites and gneisses previously reported from 28 sites, and heat production estimated from the published geochemical analyses on granites and syenites of the KKB, the new data set allows good characterization of heat production for the major granulite facies rocks and granitoids of the KKB. Garnet biotite gneisses are characterized by high levels of Th and U, with mean values of 60 and 3 ppm, respectively. Khondalites, leptynites and charnockites have slightly lower levels of Th (23, 20 and 22 ppm, respectively) and U (2.9, 2.4 and 0.9 ppm, respectively). The mean K, U, Th abundances for the granites, leucogranites and granitic gneisses ranges from 3.9 to 4.3%, 2.6 to 4.3 ppm, 22 to 50 ppm respectively, and for the syenites 4.8%, 2 ppm and 5.7 ppm. Mean radiogenic heat production values for garnet-biotite gneiss, khondalite, leptynite and charnockite are 5.5, 2.7, 2.4 and 2.2 lW m -3 , respectively. For the granites, leucogranites, granitic gneisses and syenites it is 2.6, 3.4, 4.6 and 1.4 lW m -3 , respectively. Heat production of granulite facies rocks, which are the most abundant rocks in KKB, correlate well with Th, but less with U, suggesting that variation is caused by Th and U bearing accessory minerals such as monazite and zircon. The high heat production of the KKB granulites are in contrast to the low heat production of the Late Archaean granulites of the Northern Block (NB) of the SGP which are highly depleted in radioelements and also the granulites of Madurai Block (MB) that have higher radioelemental abundances than in the granulites of the NB. The high heat production of the KKB granulites could be due to the nature of protoliths and/or metasomatism associated with Neoproteroic-to-Pan African alkaline magmatic activity represented by alkali granite and syenite-carbonatite emplacements and emplacement of pegmatites.

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Section: Geologysupporting

confidence: 73%

High radiogenic heat production in the Kerala Khondalite Block, Southern Granulite Province, India

Ray

Roy

Srinivasan

2007

Int J Earth Sci (Geol Rundsch)

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“…Correlation models undertaken by other workers further strengthen the East Gondwana connection as the Pan-African activity extends from Madagascar (cf. De Wit et al, 2001;Markl et al, 2000), SGT (Jayananda et al, 1995a;Bartlett et al, 1998;Mohan and Jayananda, 1999;Santosh et al, 2003) and Sri Lanka (Baur et al, 1991;Krö ner et al, 1994) to East Antarctica (Rogers et al, 1994;Brandon and Meen, 1995;Fitzsimons, 2000;Boger et al, 2001). However, for conclusive correlations within the Gondwana context, more geochronological and isotopic data are needed from the SGT.…”

Section: Implications Of Gondwana Reconstructionmentioning

confidence: 91%

“…Some Nd model ages indicate that differentiation of crustal protoliths from depleted mantle occurred during 3.2-2.0 Ga (Harris et al, 1994;Brandon and Meen, 1995). On the contrary, single zircon evaporation ages, together with U-Pb zircon concordia, define ages ranging from 2.5 to 2.1 Ga for the magmatic crystallization of protoliths (Bartlett et al, 1995;Jayananda et al, 1995a).…”

Section: Evolution Of Magmatic Protolithsmentioning

confidence: 95%

Ultrahigh-temperature mafic granulites from Panrimalai, south India: Constraints from phase equilibria and thermobarometry

Prakash

Arima

Mohan

2007

Journal of Asian Earth Sciences

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“…study is closely comparable to the present results. Braun, Montel & Nicollet (1998) correlated the PalaeoMesoproterozoic ages with the 2000-2700 Ga SmNd model ages reported by Choudhary et al (1992) and Brandon & Meen (1995) and interpreted them to reflect the time of first monazite growth, concluding that this provides an upper limit for the deposition of the sedimentary protoliths of the paragneisses in southern Kerala. Braun, Montel & Nicollet (1998) and Bindu, Yoshida & Santosh (1998) did not analyse zircons.…”

Section: Discussionmentioning

confidence: 99%

Depositional constraints and age of metamorphism in southern India: U–Pb chemical (EMPA) and isotopic (SIMS) ages from the Trivandrum Block

et al. 2005

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We report U–Pb electron microprobe (zircon and monazite) and Secondary Ion Mass Spectrometry (SIMS) U–Pb (zircon) ages from a granulite-facies metapelite and a garnet–biotite gniess from Chittikara, a classic locality within the Trivandrum Block of southern India. The majority of the electron-microprobe data on zircons from the metapelite define apparent ages between 1500 and 2500 Ma with a prominent peak at 2109±22 Ma, although some of the cores are as old as 3070 Ma. Zircon grains with multiple age zoning are also detected with 2500–3700 Ma cores, 1380–1520 mantles and 530–600 Ma outer rims. Some homogeneous and rounded zircon cores yielded late Neoproterozoic ages that suggest that deposition within the Trivandrum Block belt was younger than 610 Ma. The outermost rims of these grains are characterized by early Cambrian ages suggesting metamorphic overgrowth at this time. The apparent ages of monazite grains from this locality reveal multiple provenance and polyphase metamorphic history, similar to those of the zircons. In a typical case, Palaeoproterozoic cores (1759–1967 Ma) are enveloped by late Neoproterozoic rims (562–563 Ma), which in turn are mantled by an outermost thin Cambrian rim (∼515 Ma). PbO v. ThO*2 plots for monazites define broad isochrons, with cores indicating a rather imprecise age of 1913±260 Ma (MSWD=0.80) and late Neoproterozoic/Cambrian cores as well as thin rims yielding a well-defined isochron with an age of 557±19 Ma (MSWD=0.82). SIMS U–Pb isotopic data on zircons from the garnet–biotite gneiss yield a combined core/rim imprecise discordia line between 2106±37 Ma and 524±150 Ma. The data indicate Palaeoproterozoic zircon formation with later partial or non-uniform Pb loss during the late Neoproterozoic/Cambrian tectonothermal event. The combined electron probe and SIMS data from the metapelite and garnet–biotite gneiss at Chittikara indicate that the older zircons preserved in the finer-grained metapelite protolith have heterogeneous detrital sources, whereas the more arenaceous protolith of the garnet–biotite gniess was sourced from a single-aged terrane. Our data suggest that the metasedimentary belts in southern India may have formed part of an extensive late Neoproterozoic sedimentary basin during the final amalgamation of the Gondwana supercontinent.

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Nd isotopic evidence for the position of southernmost Indian terranes within East Gondwana

Cited by 56 publications

References 36 publications

High radiogenic heat production in the Kerala Khondalite Block, Southern Granulite Province, India

High radiogenic heat production in the Kerala Khondalite Block, Southern Granulite Province, India

Ultrahigh-temperature mafic granulites from Panrimalai, south India: Constraints from phase equilibria and thermobarometry

Depositional constraints and age of metamorphism in southern India: U–Pb chemical (EMPA) and isotopic (SIMS) ages from the Trivandrum Block

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